Process engineers can use the METRA HIT 28C as a calibrator and a multimeter simultaneously, for example in order to simulate sensor conditions at the input of a transmitter while measuring and saving the output signal.

If the METRA HIT BD232 plug-in infrared interface adapter (accessory) is attached to the instrument, measurement and calibration results can be uploaded to a PC, where they can be recorded and printed as a calibration report. The multimeter can

also be used as a data logger. METRAwin.10/METRAHit . PC software (accessory) allows for convenient evaluation and display of measurement data, and METRAwin.90 (accessory) can be used to create, upload and download calibration procedures, as well as for the generation of calibration certificates.

Universal Calibration Source

Integrated electronics generate mV, V and mA signals. Beyond this, the electronics are capable of simulating thermovoltages for various types of thermocouples for predefined temperatures (C orF), as well as for Pt and Ni temperature sensors.

Frequency and Pulse Generator

Continuous frequency signals can be generated by the METRAHIT 28C for testing PLCs, energy metering devices, flow rates and more. Amplitude is adjustable for the generated square-wave pulses, which are used to simulate sensor pulses. Predefined pulse runs are also generated at a chosen frequency.

Calibration and Simulation

Measuring transducers with a wide variety of input signals (voltage, thermovoltage, RTD and 2-wire resistance sensors etc.) can be directly connected and calibrated. If a multimeter is used (e.g. METRA HIT 26S), respective values can be measured at the measuring transducer's output, transmitted to a PC via an adapter if desired, displayed with the help of METRAwin.90 software and compared with the appropriate calibration specifications. Setpoint values and actual values are displayed, or printed as a certificate. When operated in the "mA sink" mode, the METRA HIT 28C simulates a 2-wire transmitter and pulls the selected current value from the device under test.

Data Storage

Individual values which have been manually saved (10 values per measuring range or sensor type), as well as complete calibration procedures are transferred to the integrated memory and can be queried one by one by pressing a key (forward or back). The calibrator is connected to a PC with the attached METRA HIT BD232 interface adapter (accessory). Individual values, intervals and ramps which have been created with the help of METRAwin.90 software can be saved as data files, uploaded to the calibrator and saved to non-volatile memory.

Read-Out Modes for Source and Sink Functions

Calibration signals can be read out either manually (numerically with key entries), or automatically by means of intervals with intermediate steps, or as a ramp signal. The METRA HIT 28C can thus be used as a precision pulse generator for dynamic testing. Depending upon individual needs, desired dynamic response can be based upon full-scale value and the number of intermediate steps (intervals), or rise and dwell periods (ramp). This is especially helpful for long-term testing of laboratory and panel recorders, as well as measuring transducers, and for "one-man" control rooms.

Numeric Read-Out

Calibration values are set and read out manually with the help of the instrument's keypad immediately after the calibration function has been selected.

Timed Output

Continuous read-out of calibration values is triggered in steps between the minimum and maximum values selected at the device to be calibrated in this read-out mode. The following step can be triggered automatically (time per step: 1 s 60 minutes), or manually.

Ramp

Continuous read-out of calibration values is triggered in a stepless fashion between the minimum and maximum values selected at the device to be calibrated in this read-out mode. Ramp duration for rising and falling ramps can be set within a range of 1 second to 60 minutes.

Temperature Simulation

The ten most common sensor types are available for the simulation of thermovoltages. Thermovoltages can be generated with reference to an internal (0 C), or an external reference junction. Temperature for the external reference junction can be set at the calibrator or with a PC. This eliminates the need to connect the device to be calibrated with the calibrator via the respectively required compensating lead. A copper conductor between the calibrator and the device to be calibrated is sufficient in this case.